What is a minor element in mineralogy ?

Minor element : definition

This term designates an element present in low but not negligible concentrations in a mineral, generally of the order of 0.1% to a few percent.
Unlike a major element, a minor element is generally not essential for the formation of a mineral and therefore is not part of the usual structural formula, although it may appear in the structural formula.
The presence of the minor element in a formula depends on the content of this element, but also on the importance that we want to give to it, for example to illustrate a phenomenon of substitution in the mineral, or to underline a particular role of stabilizer of the crystal structure of the mineral.
It is therefore a partly subjective notion : elements considered as minor for some authors may be perceived as major by others, just like trace elements in abnormally high contents...